1. Field of the Invention
The present invention relates to a semiconductor package, and more particularly to a lead frame structure for a semiconductor package having an improved dam bar structure.
2. Description of the Prior Art
In recent years, as a semiconductor package becomes largely integrated while having multi-pins therein, the pitch between leads of a lead frame also becomes minute.
As shown in FIG. 1A illustrating a plan partial view of a general lead frame, and FIG. 1B detailing portion "a" in FIG. 1A, a plurality of leads 1 including inner leads 3 provided in a molding portion 2 and outer leads 4 provided outside the molding portion 2, are connected to each other and extended from and supported by a dam bar 5 which serves to prevent the epoxy resin from externally leaking during the molding process. The dam bar 5 is completely removed by a trimming process after molding so as to prevent each of the leads 1 from being electrically shorted by the dam bar 5.
However, during the trimming process, there occurs a bending of the leads 1 due to the pressure of the cutting mold or the sweeping phenomenon in which the leads 1 are tilted and gathered to one side thereof, resulting in inferior semiconductor packages. Such a disadvantage has been more critical for a QFP package (quad flat package) which has a thinner thickness and narrower pitches between leads.
To solve the aforementioned disadvantage, a lead frame structure without a dam bar was introduced in Japanese Patent Publication No. 6-236952, and will be now described with reference to FIG. 2.
To respective upper surfaces of a plurality of leads 10 there is attached an insulating adhesive tape 11 instead of a dam bar to support the plurality of leads 10 and to prevent an epoxy resin from externally leaking.
Such a lead frame is not required to remove the insulating adhesive tape 11 functioning as the dam bar, during the trimming process to prevent the bending or sweeping phenomenon.
However, in the above-mentioned lead frame without a dam bar, the insulating adhesive tape 11 supporting the plurality of leads 10 tends to become ruptured due to the molding pressure, thus exposing the epoxy resin.